Читать книгу Noises from the Darkroom: The Science and Mystery of the Mind - Guy Claxton - Страница 22

In simple multicellular creatures, a nervous system that keeps the different subsystems directly in touch with one another will do well enough. They can talk to each other by CB radio, without having to invest in any central administration. The Portuguese man-of-war, for example, is technically speaking not a single creature but a large sticky conglomerate of interdependent organisms who have decided to throw in their evolutionary lot with each other. Some of these are specialized for floating and providing buoyancy. Others engage in collecting and digesting of food, or in sensing different forms of incoming energy (who can tell by the stimulation of the water whether there is anything interesting in the vicinity, and if so whether it is likely to be a meal or an enemy). Others specialize in mounting guard and manufacturing ammunition for the poisonous tentacles. And others in planning and preparing for reproduction. This colony manages to co-ordinate its complicated set of senses, activities and needs without any central information point, or sophisticated nervous system, simply by enabling various sensory and response subsystems to talk directly to each other.¹⁷

Beyond a certain degree of complexity, however, this point-to-point form of communication begins to become cumbersome and inadequate. The system as a whole needs to be able to hold ‘conference calls’, as well as allowing each department to talk directly with one another. So evolutionarily there is a move towards greater ‘networking’ between the different systems, and eventually towards some kind of centralization – an office, like that which controls a fleet of taxicabs, which can keep an overview of what is going on, and co-ordinate the different activities. And at this point the distributed nervous system begins to develop into a ‘central nervous system’, the CNS. Not that there has to be any controller who sits in the ‘head office’, deciding what is best. The design of the animal CNS, and ultimately of its brain, as we shall see, is such that this kind of centralized decision-making about what is best for ‘all-of-me’, can be conducted very well by a communication system that is wired up in clever ways, so that the wiring itself determines how choices are made. No ghost in the machine is required.